Processing chambers used for making semiconductor devices involve deposition and etching processes performed in vacuum environments. These processes also require plasma chemistries to etch or deposit conductors and dielectric materials on various substrates (wafers). These wafers are mostly made of Si, but may also be made of GaAs or GaN. During such plasma processes, where plasma generated chemistries are directed towards a wafer by means of voltage biasing or electromagnetics, the walls and components of the processing chambers that surround a wafer are also exposed to those etching chemistries. The etching of material from the chamber walls and various components inside the vacuum chamber results in particle generation, which is undesirable. These particles can land on the wafers and result in damage to the critical submicron features and functionality of the semiconductor devices that that are being etched or deposited thereon. Currently, there is a growing need to make these submicron critical features smaller and smaller to make even denser semiconductor devices. These submicron features have critical dimensions, and the future generation of semiconductors is moving toward a critical size of the order of 20 nm and beyond. Such a reduction in the critical dimensions requires further reductions of particle generation inside these process chambers.
Particle generation from the chamber walls in a semiconductor chamber/member can lead to other problems, as well. The physical presence of eroded metallic particles in parts per million on a process wafer can also cause electrical shorting between two nearby conductors. In addition, if the generated particles diffuse into the wafer matrix, they can result in uncontrolled ion mobility, thereby causing the semiconductor device to malfunction. The success of these nanometer devices and the critical features thereof therefore require that the walls of the process chambers are protected from plasma erosion. And if walls are eroded, it is important that very few particles are released on to a wafer that could possibly cause any malfunctions of the formed devices.
One method of providing such protection from particle generation involves using thermal sprayed coatings that are resistant to plasma erosion. An initial approach to chamber wall protection focused on anodization, and thermal sprayed coatings made of Al2O3 became a material of choice. U.S. Pat. No. 4,419,201 discloses the use of Al2O3 coatings to resist erosion caused by chlorine plasma. U.S. Pat. No. 5,637,237 further discloses a plasma etch chamber where the chamber wall surfaces are coated with Al2O3, Y2O3 and Sc2O3 to reduce erosion of walls exposed to plasma. The recent introduction of aggressive, high density fluorine plasma results in the rapid etching of Al2O3 coated chamber walls and the generation of AlF particles. The AlF particles form dust inside the process chamber, have proven to be difficult to remove, and cause wafer-level defects in semiconductor devices.
Y2O3 coatings then became a material of choice, however, the use of Y2O3 coatings has also resulted in problems. That is, while yttria coatings have been successful in resisting fluorine plasma erosion, these coatings rapidly erode when exposed to chlorine plasma. Another drawback of yttria coatings is the delamination of these coatings when exposed to aqueous cleaning processes outside the semiconductor chambers. The presence of yttrium fluoride and yttrium oxyfluoride particles has also caused problems at the wafer-level. As a result, a number of publications and patents have addressed the need for improvements in yttria coatings to solve these various problems.
For example U.S. Pat. No. 6,776,873 discloses combining Al2O3 with Y2O3 to provide resistance to fluorine and oxygen plasma. U.S. Pat. No. 7,494,723 discloses a method of densifying a top layer of a Y2O3 coating with e-beam radiation to provide increased erosion resistance. U.S. patent application publication No. 2010/0272982 A1 describes the use of yttria stabilized zirconia coatings that provide plasma erosion resistance and wet cleaning resistance. U.S. Patent application publication No. 2012/0177908 A1 discloses the use of a porosity gradient in Y2O3 and Zr2O3 coatings to gain higher thermal resistance in addition to plasma resistance. U.S. patent application publication 2012/0196139 A1 describes a multilayer coating structure to gain plasma erosion resistance and wet cleaning resistance. U.S. patent application publication No. 2015/0376760 A1 and International Publication No. WO 2015/199752A1 disclose providing controlled emissivity coatings for chamber components to gain thermal enhancement and improved plasma erosion resistance.
However, all of these earlier solutions are based on the use of single oxide materials classified as AO, where A is a metal and O is the oxide; like Al2O3, Y2O3, Ce2O3, Gd2O3, HfO2, ZrO2, etc. As such, there is still a need to understand the benefits provided by the use of multicomponent, complex oxides with respect to improved resistance to plasma erosion and subsequent wet cleaning resistance to provide the next generation of productivity solutions for the semiconductor processing members.
The processes used in semiconductor chambers are also evolving and a new generation of coating materials is desired that can provide needed solutions beyond yttria. One of the needs is to have coating materials that can withstand both fluorine and chlorine plasma inside the chamber, thereby preventing particle generation. It is also desired that these materials should have sufficient dielectric strength to withstand the voltages present in a semiconductor process chamber. In addition to the plasma erosion resistance inside these vacuum tools, the coatings must also provide resistance to spallation and/or erosion when the components are later wet cleaned to remove materials deposited during various semiconductor etching or deposition processes.
To address the prevention of erosion of the semiconductor chamber components, the prior art has heretofore been focused on the use of single oxides, and no recognition has been made with respect to the use of complex oxides, where all of the oxides are in a solid solution and have a controlled purity of specific elements in ppm.